1. Field of the Invention
The preset invention relates to a preventive maintenance management system and method for monitoring preventive maintenance data of a machine and generating a maintenance schedule for the machine, and relates to a cell controller included in the system.
2. Description of the Related Art
In a system (such as a production system) including a plurality of machines, each machine may be operated by a plurality of numerical controllers for controlling the respective machines, based on a command from a supervisory computer. As a relevant prior art document, JP 2004-202624 A discloses a method and a device for periodically collecting information from a plurality of robots connected to a network, and accumulating a status of each robot in a database. JP 2004-202624 A also describes that, when a malfunction occurs in one robot, it can be judged as to which robot will have a malfunction, based on information of a previously registered robot and information obtained in real-time.
Further, JP 2004-062276 A discloses a device information delivery unit having a means for periodically collecting device information of a machine tool or a measurement device at predetermined time intervals, accumulating the collected device information associated with a timing of the collection in a database, and transmit the accumulated device information to external equipment.
On the other hand, there is a conventional device having a function for informing an operator of when each component used in a machine tool should be checked. For example, JP 2014-174680 A discloses a numerical controller having such a function.
JP 2003-036320 A discloses a component information processing system including: an accumulating means which accumulates operational conditions of replaceable components in a device as accumulated operational information; a life information storing means which stores life information representing operational limits in operating the replaceable components; an operation-for-a-period information storing means that stores operation-for-a-period information representing operational conditions of the replaceable components over a predetermined period of time; a replacement timing calculating means which calculates timing when the replaceable components must be replaced based on the operation-for-a-period information, the accumulated operational information and the life information; and an outputting means which outputs the calculated timing of the replacement.
Further, JP 2002-123314 A discloses an optimization system for maintenance of a plant, including (1) a means for analyzing and quantitatively evaluating material deterioration, corrosion trends, etc., by high-level technology as to secular changes of plant equipment materials, and also quantitatively evaluating a fault of operating equipment based on failure mode effect analysis; (2) a means for quantitatively specifying maintenance portions based on the quantitative evaluation; and (3) a means for setting an occurrence frequency of a fault and a degree of influence of the fault by using an influence degree evaluating method, and evaluating (the frequency*the influence degree) as a risk.
In the prior art, in many cases, the replacement of a component of each machine due to deterioration thereof is carried out by an operator, when used hours of the component exceeds a predetermined period of time, since the component can be considered to be deteriorated in such a case. However, in such a method in which the component is replaced after the predetermined of period of time has elapsed, a component which is not actually deteriorated may be replaced, which is very wasteful.
In another conventional method, a numerical controller outputs an alarm, etc., for demanding the replacement of a component to the outside (or an operator), based on a condition such as a threshold relating to the deterioration of the component. However, in some cases, a (residual) period of time until the component comes to the end of its life (or becomes unusable) is very short. In such a case, the component may become unusable before the replacement operation for the component is finished, even though the operator starts the replacement operation after the alarm is output, whereby a productive efficiency, etc., may be significantly lowered. In the technique of JP 2004-202624 A or JP 2004-062276 A, such a residual period of time is not calculated.
On the other hand, in JP 2014-174680 A, although the numerical controller calculates the time intervals for checking the component and outputs them to the outside, the residual period of time as described above is not calculated or output. In JP 2003-036320 A, the life of the component is calculated based on the operation information thereof, not on the actual status of the component. Therefore, if the actual life of the component is significantly deviated from the life information in the past, it is difficult to replace the component at an appropriate timing. Further, in JP 2002-123314 A, although the deterioration or corrosion of the plant equipment material is quantitatively evaluated and the maintenance portion is specified so as to evaluate the risk, the residual period of time is not correctly calculated based on the actual status of the component.